Multioffice automatic telephone system



May 23, 19330 A. J. RAY

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MULTIOFFIGE' AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 4. 1922 v Patented May 23, 1933 UNITED STATES PATENT; OFFICE ARTHUR J. RAY, OF CHICAGO, ILLINOIS, ASSIGNOR, IBY MESNE ASSIGNMENTS, TO ASSO- CIATED ELECTRIC LABORATORIES, INC, OF CHICAGO, ILLINOIS, A CORPORATION O]? DELAWARE MULTIOFFICE AUTOMATIC TELEPHONE SYSTEE Application filed November 4, 1922, Serial No. 599,022. Renewed November 19, 1926.

The present invention relates to multi-ofiice automatic telephone systems in general, but

is concerned more particularly with multioiiice automatic telephone systems in which there art two difierent types of automatic offices, and the principal object, stated briefly, is the production of new and improved circuit arrangements for handling calls which come into a so-called panel office from a so-called step by step oflice.

In order to explain the necessity for an arrangement such as is contemplated by the present invention, it may be stated that, in many cities served by a multi-ofiice telephone system, for reasons which vary with diflerent cases, two widely different kinds of automatic equipment, namely; the step by step type and the panel type, are installed in different oflices of the system. When this is done, special arrangements must be made when calls originating in a step by step automatic office (in which the switches are directly controlled and operate in a step by step manner) are intended for a panel oilice (in which the switches are power-driven and are operated according to the well-known I revertive control system).

In order to meet the situation, each of the trunks from a step by step automatic 0ffice to a panel office is carried to the panel ofiice and terminated in a trunk circuit in dividual to an incoming panel selector. There is a secondary switch associated with each trunk circuit. These secondary switches have common access to a plurality of register sets and an idle register set is seized by one of these secondary switches when the trunk associated with the secondary switch is seized. Then, when the remaining digits in the desired number are received, the register set is correspondingly operated, after which the register set is temporarily associated with an idle sender and the number which is set up on the register is quickly transferred to the set-up relays of the sendout showing how the sheets of drawings fit together.

The equipment shown in Fig. 1 is automatic equipment of the well-known type and comprises the substation A, of which the lllle terminates in the individual line switch C, the district selector D accessible to the line switch C, the ofiice selector E (denoted by the dotted rectangle bearing that reference character) accessible to the selector D, and the automatic repeater F which is accessible to the oilice selector E and which is individual to the trunk comprising conductors 72 and 73.

The inter-oifice trunk comprising conductors 72 and 73, terminates at the panel oflice in the trunk circuit TC, Fig. 2, which is individual to the incoming selector, Fig. 4. The incoming selector, Fig. 4, has access to a number of final selectors, of which the final selector shown in Fig. 5 is one.

The secondary switch SS, Fig. 2, associated with the trunk circuit TC has access to a number of register sets, of which the register set shown in Fig. 6 is one. This register set is adapted to register the four digits in the called subscribers number.

The register allotter, Fig. 7, allots the register sets one at a time after the full number has been dialled on each one and causes the energization of the register connecting relay, such as 428, so as to connect the conductors of the register set through to the common transfer control circuit, Fig. 8.

Associated with the transfer control circuit, Fig. 8, there are six finder selectors, of which one is shown in Fig. 9. The trunk finding element of each of these finder selectors has access to all the incoming selectors of the associated group, and the selector element has access to a group of senders of which the sender shown in Figs. 10 and 11 is 10 wipers have no normal position and move in a orward direction only. The secondary switch SS, Fig. 2, as well as the register allotter, Fig. 7, is mechanically similar to the line switch 0.

The selector switches D and E, Fi 1, are step by step automatic switches of t e wellknown vertical and rotary type and each has 100 sets of bank contacts arranged in ten horizontal rows or levels. The registers R and R, Fig. 6, are mechanically similar to the selectors D and E, Fig. 1.

The panel type selector switches which are shown in Figs. 4 and 5, may be of the type described in Patent No. 1,123,696 to Craft et al, issued January 5, 1915. The finder and selectorswitches of the finder-selector link, Fig. 9, are identical with each other except as regards the number of brushes provided,

and are similar to ,the selector switches.

.to Reynolds et al.

The apparatus, having been described generally, will now be described in connection with a detailed description of its operation. For this purpose, it will be assumed that the v subscriber at substation A, Fig. 1, whose line terminates in the step by step automatic office, desires to obtain connection with the subscriber at substation A, Fig. 5, whose line terminates in the panel automatic oflice. It will be assumed by way of illustration that the panel ofiice is ofiice 26 and, that the number of the subscriber at substation A is 3737. Consequently, the complete number to be dialled is 2637 37, a dash being inserted ordinarily between the ofiice designation and the subscribers number to enable the calling subscriber to remember the desired number without diificulty.

When the receiver is removed at substation A, line relay 6 energizes over line conductors 2 and 4. Upon energizing, line relay 6 places ground on private normal conductor 3 at armature 10', thereby making the calling line busy and closing a circuit for switching relay 5 and stepping magnet 7 in series. As a further result of the energization of line relay 6, it connects test wip- -contact of armature 44 an er 12 to the junction of switching relay 5 and stepping magnet 7 at armature 8'.

In case the trunk upon which the wipers of the line switch are standi is idle, switching relay 5 ener izes imme iately. Assuming the trunk to busy however, switching relay 5 is short circuite and does not enerize, and the wipers are rotated step by step y the buzzer-like action of stepping magnet 7, which operates from ound on the busy test contacts encounter by test wiper 12. When an idle trunk is reached, which trunk it will be assumed is'the one comprisin conductors 17-19, inclusive, switching re ay 5, being no longer short circuited energizes in series with stepping magnet Stepping magnet 7, however, does not energize at this time on account of the high resistance of switching relay 5. Switching relay 5, upon energizing, opens a point in the test circuit and prepares the holding circuit at armature 9, and at armatures 8 and 10 disconnects line conductors 2 and 4 from the winding of line relay 6 and ground, and extends them by way of wipers 11 and 13, bank contacts 14 and 16, conductors 17 and 19, and armatures 42 and 45 and their resting contacts to the upper and lower windings of line relay 25 of the selector D.

Line relay 25 now energizes over the calling subscribers loop and closes at armature 36 a circuit for release relay 26. Upon energizing, release relay 26 opens a point in the circuit of release magnet 30 and prepares a circuit for vertical magnet 35 at armature 38, and at armature 37 places ground on release trunk conductor 18, thereby closing the usual holding circuit for switching relay 5 of the line switch C before slow acting line relay 6 has had time to deenergize.

When the calling subscriber operates his calling device in accordance with the first digit 2 in the desired number of the desired oflice, the circuit of line relay 25 is opened a corresponding number of times. Each time line relay 25 deenergizes in response to one of .the interruptions thereby produced, it closes a circuit for vertical magnet 35 as follows: From ground by we of the resting said armature, armature 36 and its resting contact, armature 38 and its working contact, relay 27, and vertical magnet '35 to battery. By the operation of vertical magnet 35, the wipers 46- 48, inclusive, are raised opposite the fifth level of bankcontacts. Relay 27 is energized in series with vertical magnet 35 and, being slow acting, retains its armature attracted throughout the vertical movement. As a result of the energization of relay 27 it closes a circuit at armature 39 for stepping relay at armature 40, and at armature 41 prepares a circuit for rotary magnet 32.

At the end of the vertical movement, slow acting relay 27 deenergizes and completes the circuit of rotary magnet 32 at armature 39. Rotary magnet 32, upon energizing, advances the wipers 46-48, inclusive, into engagement with the first set of bank contacts in the selected level, and, near the end of its stroke, opens the circuit of stepping relay 28 at interrupter contacts 33. Stepping relay 28, upon deenergizing, opens the circuit of rotary magnet 32 at armature ,41, whereupon rotary magnet 32 deenergizes also and closes its interrupter contacts 33 again. In case the trunk terminating in the first set of bank contacts is idle, switching relay 29 energizes immediately. Assuming the trunk to be busy, however, switching relay 29 is short circuited by the ground. potential encountered by test wiper 47 and stepping relay 28 energizes from this same ground potential and closes the circuit of rotary magnet 32 again, whereupon the switch wipers are rotated into engagement with the next set of bank contacts. 1

This alternate operation of stepping relay 28 and rotary magnet 32 continues until an idle trunk is reached, which trunk it Will be assumed is the one extending to the second or ofiice selector E, whereupon switching relay 29, being no longer short circuited, energizes in series with stepping relay 28. Stepping relay 28, however, does not energize at this time on account of the high resistance of switching relay 29. Switching relay 29, upon energizing, opens a point in the test circuit and prepares the holding circuit at armature 43; disconnects ground from armature 35 of line relay 2 at armature 44, thereby opening the circuit of release relay 26; and at armatures 42 and 45 disconnects conductors 17 and 19 from the windings of line relay 25, and extends them by way of wipers 46 and 48 to the line relay of the selector E. The line and. release relays (not shown) of the selector E now energize and prepare the switch for operation, and the latter relay grounds the release trunk conductor, thereby establishing the usual holding circuit for the switches C and D. v

In response to the calling of the second digit 6 in the number of the desired oflice, the wipers of the oflice selector E are raised opposite the level of bank contacts in which the trunks extending to the panel ofiice terminate, and are then rotated in search of an idle trunk in the usual manner. In this case, it will be assumed that the trunk extending to the repeater F and comprising conductors 49-51, inclusive, is the one selected. That being the case, line relay 62 of the selector F energizes overthe calling subscribers loop and through the normally closed contacts controlled by armatures 65 and 66 of reversing relay 61, and closes a. circuit for release relay 63 at armature 67. Release relay 63, upon energlzing, prepares a circuit for relay 64 at armature 70, and at armature 69 places ground on release trunk conductor 50, thereby establishing the usual holding circuit for the switches C, D, and E. As a further result ofthe energization of line relay 62, it closes a bridge across the outgoing trunk conductors 72 and 73 at armature 68. This bridge, it will be noted, includes the right-hand windings of the repeating coil and the lower windmg of the electro-polarized reversing relay 61 Reversing relay 61 does not energize at this time, however, for the reason that the current flow in either winding opposes the eurrent'fiow in the other winding.

In the panel office, line relay 102 energizes over conductors 72 and 73 and through the left-hand repeating coil windings and the normally closed contacts cont-rolled by armatures 109 and 110 of reversing relay 101, in response to the closure of the previously mentioned bridge across conductors 72 and 73 in the repeater F. Upon energizing, line relay 102 closes a circuit for release relay 103 at armature 112. Release relay 103, upon energ1z1ng, closes at armature 113 a circuit for switching relay 141 and stepping magnet 142 of the secondary switch SS in series as follows: From ground by way of the Working contact of armature 113 and said armature, armature 117 and its resting contact, armature 120 and its resting contact, switching relay 141, and stepping magnet 142 to battery. As a further result of the energization of release relay 103, it connects test wiper 149 to the junction of switching relay 141 and of the resting contact of armature 118 and sald armature, armature 121 and its resting contact, and the resting contact of armature 145 and said armature.

In case the trunk upon which the wipers of the secondary switch are standing is idle, switch ng relay 141 energizes immediately. Assum ng the trunk to be busy, however, switchlng relay 141 is short circuited by the ground potential which is found on the test contact thereof by test wiper 149, and the wipers are rotated step by step in search of an idle trunk by the buzzer-like action of stepplng magnet 142. When an idle trunk 1s found, which trunk it will be assumed is the one comprising conductors 155158, inclusive, and terminating in bank contacts stepping magnet 142 at armature 115 by way 151154, inclusive, switching relay 141 enerv and 146 connects up wipers 147 148, and 150, respectively.

In the seized register set relay 362 energizes in response to the ground potential being placed on wiper 149, by armature 145 of switching relay 141, over a circuit which includes release trunk conductor 156 and armature 372 and its resting contact. Relay 362,

upon energizing, opens a point in the circuit of release magnets 369 and 478 of the registers R and R, respectively, and places ground on looking conductor 399 at armature 375; opens a point in the circuit of busy relay 361 at armature 374; and at armature 373 connects up the lead from the common interrupter 372 for a purpose which will be explained subsequent y.

When the calling subscriber operates his calling device in accordance with the first digit 3 in the number of the desired subscriber, the circuit of line relay 62 of the repeater F in the step by step ofiice is interrupted three times. Each time line relay 62 deenergizes in response to oneof these interruptions, it opens at armature 68 the circuit of line relay 102 of the trunk circuit TC in the panel oflice. As a further result of each deenergization of line relay 62 of the repeater F, it closes at armature 67 a circuit for relay 64 by way of armature 70 and its working contact. Relay 64 energizes in response to the first closure of its .circuit and, being slow acting, retains its armature attracted throughout the series of impulses, and at armature 71 completes the bridge across conductors 72 and 73 by way of a direct path which excludes the right-hand repeating coil windings and the lower winding of electro-polarized relay 66. This is the usual expedient which is made use of in impulse repeaters to switch from a talking circuit to a dialling circuit.

In the panel ofiice, line relay 102 of the trunk circuit TC, deenergizes in response to each of the above-named interruptions produced in its circuit by the line relay of the repeater F at the automatic ofiice and, upon each deenergization, sends an impulse of cur rent over operating conductor 155, at armature 112, by way of the working contact of armature 114 and said armature, armature 143 and its workin contact, wiper 147, and bank contact 151. Each of the impulses in this series is transmitted from impulse conductor 155 to vertical magnet 370 of the register R, the first impulse of current beingtransmitted as follows: From ground by way of the previously traced circuit to impulse conductor 155 and thence by way of the resting contact of off normal spring 368 and said spring, relay 363, and vertical magnet 370 to battery. By the operation of vert cal magnet 370, the switch wipers 431-436, Inclusive, are raised step by step until they stand opposite the desired level of bank contacts, which in this case is the third. Relay 363 is energized in series with vertical magnet 37 0 and,

ing slow acting, retains its armature attracted throughout the series of impulses, thereby maintaining its own circuit and that of vertical magnet 370 intact after the off normal springs have shifted as they do upon the first vertical ste At the end of the series of impulses, re ay 363 deenergizes and transfers the operating circuit from the vertical to the rotary magnet.

When the calling subscriber manipulates his calling device in accordance with the next digit 7 in the desired number, a correspondmg number of impulses is sent over operating conductor 155 as before. Each of the seven impulses in this series is delivered to rotary magnet 371, the first impulse being delivered by way of the following circuit: From ground by way of the circuit as previously traced to operating conductor 155, and thence by way of the normally open contacts controlled by ofl normal spring 368, armature 376 and its resting contact, resting contact of armature 378 and said armature, relay 365, and rotary magnet 371 to battery. By the operation of rotary magnet 371, the wipers of the register R are rotated into engagement with the desired set of bank contacts in the third level, being the seventh set in this case. Relay 365 is energized in series with rotary magnet 371 and, being slow acting, retains its armature attracted throughout the rotary movement. 2 Upon energizing, relay 365 places a shunt around armature 378 and its resting contact at armature 380 and at armature 381 closes a circuit for relay 364 from the grounded conductor 399. Relay 364, upon energizing, closes a locking circuit for itself at armature 379; prepares a circuit for vertical magnet 479 at armature 377 and at armature 378 opens a point in the circuit of rotary magnet 371 and relay 365, leaving the circuit established through armature 380 and its working contact. At the end of the rotary movement, relay 365 deenergizes and shifts the operating circuit from rotary magnet 371' to vertical magnet 479 of the register R at armature 380. v a

When the next digit 3 in the desired subscribers number is sent, the resulting train of impulses coming in over operating conductor 155 are sent to vertical magnet 479 of the register R, the first impulse being sent over the following circuit From ground by way of the circuit as previously traced to armature 380 and thence by way of the resting contactof armature 380, working contact of armature 377 and said armature, contact of oil normal spring 483 and said spring, series relay 473, and vertical magnet 479 to battery. By the operation of vertical magnet 479, the wipers 441-446, inclusive, of the register R are raised opposite the desired maintained energized during the vertical movement of the register R and, like the corresponding relay 363 of the register R, malntains itsown circuit and that of the associated vertical magnet intact after the oil normal springs have shifted upon the first vertical step of the switch. At the end of the vertlcal movement of the register R, slow acting relay 473 deenergizes and transfers the operating circuit from the vertical magnet 479 to the rotary magnet 480.

When the train of impulses representing the next and last digit 7 in the desired subscribers number is transmitted, rotary magnet 480 is energized a corresponding number of times, the first energization being effected over a circuit which extends from ground as previously traced to armature 377 and thence by way of the normally open contacts controlled by ofi' normal spring 483, armature 484 and its resting contact, resting contact of armature 488 andsaid armature, relay 475, and rotary magnet 480 to battery. Slow acting series relay 475 is maintained energized during the rotary movement in series with rotary magnet 480. Upon energizing, relay 475 opens a point in the circuit of relay 476 and closes a circuit for relay 474'at armature 489 from grounded conductor 399. Relay 474, upon energizing, locks itself to conductor 399 at armature v486, and prepares a circuit for relay476 at armature 487. At the end of the rotary movement, relay 475 deenergizes and completes a circuit for relay 476 at armature 489. Relay 476, upon energizing, disconnects relay 475 and rotary magnet 480 at armature 488; removes ground from test conductor 425 and places ground on holding conductor 424 at armature 490; and at armature 491 places ground on the common start conductor 423.

Assuming the register allotter, Fig. 7, to be idle, start relay 429 is energized through the resting contact of armature 426' and said armature in response to the placing of ground on start conductor423; closes a circuit for switching relay 430 and stepping magnet 428 in series at armature 448; and at armature 447 connects test wiper 438 to the junction of switching relay 430 and stepping magnet 428.

In case the wipers of the register allotter are standing on the bank contacts in which conductors 424-426, inclusive, terminate, switching relay 430 energizes immediately. However, assuming the wipers to be standing on some other set of bank contacts, switching relay 430 is short circuited by the ground potential encountered by test wiper 4.38 and does not energize, and the wipers are rotated step by step in search of the waiting register set by stepping magnet 428, which operates in a buzzer-like manner from ground picked up by test wiper 438. When the set of contacts in which conductors 424-7426, in-

clusive, terminate is reached, switching relay 430, being no longer short circuitcd, encrgizes in series with stepping magnet 428. Stepping magnet 428, however, does not energize at this time on account of the high resistance of switching relay 430. Upon energizing, switching relay 430 locks itself to the grounded holding conductor 424 at armature 499; places ground on conductor 426 at armature 449 by way of armature 427 and its resting contact and wiper 440; and at armature 426' disconnects line relay 429 from the common start conductor 423, whereupon line re.- lay 429 deenergizes.

In response to ground being placedon conductor 426, relay 428 energizes and connects conductors 411422,inclusive, and 157 of the register set with the common conductors 451458, inclusive, and 460464, inclusive, respectively, of the transfer control circuit, Fig. 8. As a further result of the energization of relay 428, it places ground on conductor 459, whereupon relay 567 of the transfer control circuit, Fig. 8, energizes through the lower right-hand contact of sequence switch cam 582 and said cam, sequence switch 550 being in position 1 or position 10. The energization of relay 567, however, does not have any immediate efi'ect. As a still further result of the energization of relay 428, it places ground on the conductor 158; thereby grounding assign conductor 129 of the incoming selector through bank contact 154 of the secondary switch SS, wiper 150, and the working contact of armature 146 and said armature. When this occurs, relay 106, in the trunk circuit TC, energizes and closes a locking circuit for its lower winding at armature 123, and at armature 122 removes ground from release conductor 127 of the incoming selector for a reason that will appear more fully hereinafter.

In the incoming selector, Fig. 4, in response to ground being placed on assign conductor 129 by way of a previously traced circuit, sequence switch 200 is moved out of position 1 upon its magnet being energized from assign conductor 129 and through the upper left-hand contact of cam 232 and said cam. Sequence switch 200 stops in position 2 to await the trunk finder, Fig. 9. In position 2, sequence switch 200 grounds the common start conductor 246 by way of the lower lefthand contact of earn 219 and said cam, armature 210 and its resting contact, and cam 225 and its lower left-hand contact. It will be noted that start conductor 246 traverses Figs. 3, 8, and 12, and from thence extends to all the finder selectors, such as the one shown in Fig. 9. Assuming the finder selector allotter to be in position 1, the sequence switch of finder selector No. 1, which is the one shown in Fig. 9, is in position 1 while the sequence switches of the other finder selectors are in other positions. With the assumption as noted, relay 617, Fig. 9, is energized from ground on start conductor 246 through the lower left-hand contact of cam 543 and said cam, (sequence switch 600 being in position 1) the upper right-hand contact of cam 643, and relay 617 to battery. Upon energiz ing, relay 617 closes a locking circuit for itself at armature 626 as follows: from ground by way of commutator brush 663,

commutator 665, upper left-hand contact of cam 635 and said cam, armature 626 and its working contact, and relay 617 to battery. As a further result of the energization of relay 617, it closes at armature 627 a circuit for the lower winding of relay 616 as follows: from ground by way of armature 627 and its working contact, upper right-hand contact of sequence switchcam 652 and said cam, upper left-hand contact of cam 652, and the lower winding of relay 616 to battery. Relay 616, upon energizing, closes a circuit for sequence switch 600 as follows: from ground by way of armature 625 and its working contact, upper right-hand contact of sequence switch cam-647 and said cam, and the magnet of sequence switch 600 to battery. When sequence switch 600 reaches position 1%, the previously traced locking circuit for rela 617 is supplemented by one which is as to lows: from ground by way of cam 640 and its upper left-hand contact, armature 621 and its resting contact, upperright-hand contact of cam 635 and said cam, armature 626 and its working contact, and relay 617 to battery. When sequence switch 600 reaches position 2, a circuit is closed for up-drive magnet 659 of the trunk finder as follows: from ground by way of armature 627 and its working contact, upper right-hand contact of cam 652, and up-drive magnet 659 to battery.

In response to the energization of up-drive magnet 659, the elevator of the trunk finder is raised vertically and brushes 66967 2, inclusive, are made to pass over their associated bank contacts in search of the trunk on which the call is waiting.

As a further result of the sequence switch 4 600 coming into position 2, a circuit is closed for up-drive magnet 601 of the sender selector asfollows: from ground by way of armature 625 and its working contact, upper right-hand contact of sequence switch cam 642 and said cam, lower right-hand contact of cam 642, and up-drive magnet 601 to battery. Consequently, brushes 605608, inclusive, of the sender selector are started upward in search of an idle sender at the same time that the brushes 669-673, inclusive, of

switch 600 is moved out of position 2 and into position 3 and when the sender selector has selected an idle sender, sequence switch 600 is moved out of position 3 and into position 4, provided the sequence, switch 600 has been moved into osition 3 in response to the trunk finder finding the waiting trunk.

When the brushes 669-673, inclusive, of the trunk finder arrive upon the set of terminals in which conductors 247251, inclusive, of the waiting trunk terminate, brush 670, upon making contact with its associated terminal in the above named set,closes a circuit for relay 615 as follows: from ground by way of the lower lefthand contact of sequence switch cam 221, Fig. 4, and said cam, upper right-hand contact of cam 221, (sequence switch 200 being in position 2) armature 211 and its resting contact, upper right-hand contact of cam 224 and said cam, lower right-hand contact of cam 224, c0nductor 250, brush 670, lower left-hand contact of sequence switch cam 636 and said cam, and relay 615 to battery. Relay 615, upon energizing, opens the second traced locking circuit of relay 617 at armature 621, leaving relay 617 ener ized by way of its locking circuit which inc udes stri 655 and commutator brush 663. When e brushes have become centered upon the contacts, brush 663 comes into engagement with an insulated portion of the strip 655, thereby opening the first locking circuit of relay 617, whereupon relay 617 deenergizes and opens the circuit of up-drive magnet 659 at armature 627. When this occurs, the brushes of the trunk finder stop. As a further result of the energization of relay 615, it closes a locking circuit for itself at armatures 621 as follows: from ground by way of cam 640 and its upper left-hand contact, armature 621 and its working contact, upper left-hand contact of cam 636 and said cam, and relay 615 to battery. As a still further result of the energization of relay 615, it closes a circuit for relay 614 at armature 622 by way ing, connects up wiper 669 at armature 619;

connects .up wiper 671 at armature 618; and

at armature 620 connects'up wiper 673, thereby completing the holding circuit for relay 615 as follows: from ground by way of the lower'left-hand contact of cam 221 and said cam, upper right-hand contact of cam 221, armature 211 and its resting contact, upper right-hand contact of cam 224 and said cam, upper left-hand contact of cam 224, holding conductor 247, brush 673, armature 620 and its working contact, armature 621 and its working contact, upper left-hand contact of cam 636 and said cam, and relay 615 to bat- I tery. The closure of its locking circuit enables relay 615 to remain energized after its first traced locking circuit has been opened at cam 640 upon sequence switch 600 moving beyond position 3. Relay 617, in addition to opening the circuit of up-drive magnet 659. as described, upon falling back, closes a circuit for sequence switch 600 as follows: from ground by way of armature-627 and its resting contact, upper right-hand contact of cam 650 and said cam, and the magnet of sequence switch 600 to battery. The sequence switch 600 now moves from 'position 2 into position 3 to wait until the operation of the sender selector is completed.

The operation of the sender selector will now be taken up. Vith the sequences switch 600 in position 2 or position 3, it will be noted that relay 616, which relay energized initially upon the energization of relay 617, as described, is energized through a commutator brush 610 of the sender selector over a circuit which extends as follows: from ground by way of cam 641 and its upper right-hand contact, working contact of armature 623 and said armature, cam 644, and its upper right-hand contact, commutator brush 610, strip 612, upper right-hand contact of cam 639 and said cam, and the upper winding of relay 616 to battery. liVhen commutator brush 610 reaches the first insulated segment of the commutator 612, the brushes 605-608, inclusive, are in engagement with the first set of terminals and, assuming the sender terminating in those terminals to be busy, relay 616 is held energized by its lower winding over the following circuit: from ground encountered by brush 607, lower right-hand contact of cam 645 and said cam, lower lefthand contact of cam 645, armature 624 and its working contact, cam 648 and its lower lefbhand contact, and the lower Winding of relay 616 to battery. Consequently, the updrive movement continues until an idle sender is found, which sender, it will be assumed, is the one shown in Figs. 10 and 11. When the terminals of said idle sender is reached, commutator brush 610 is in engagement with an insulated segment, and, consequently, the circuit for the upper winding or relay 616 is opened. Also, since the sender shown in Figs. 10 and 11 is idle, test conductor 752 is not grounded and no circuit is closed for the lower winding of relay 616 and relay 616 deenergizes and opens the circuit of up-drive magnet 601 at armature 625, at the same. time closing a circuit for sequence switch 600 as follows: from ground by way of armature 625 and its resting contact, upper left-hand contact of cam 647 and said cam, and the magnet of sequence switch 600 to battery. Sequence switch 600 now moves from position 3 into position 4.

With sequence switch 600 in position 4, a circuit is closed for relay 712 of the selected sender, (Fig. 10) as follows: from ground by way of armature 629 of relay 614 of the finder selector, Fig. 9, and its working contact, upper left-hand contact of sequence switch cam 649 and said cam, lower right-hand contact of cam 649, brush 605, conductor 750, cam 703 and its lower left-hand contact, (sequence switch 700 being in position 1) and the upper winding of relay 712 to battery. Relay 712, upon energizing, closes a circuit for sequence switch 700 at armature 717 by way of the lower left-hand contact of cam 704 and said cam. Sequence switch 700 now moves from position 1 to position 2. As a further result of the energization of relay 712, it closes a locking circuit for itself at armature 716 as follows:

from ground by way of the upper left-hand contact of cam 645, Fig. 9, and said cam, lower right-hand contact of cam 645, brush 607, conductor 752, armature 716 and its working contact, and relay 712 to battery. When sequence switch 700 reaches position 2, the lower winding of relay 712 is connected up at its lower terminal by cam 702. This, however, does not have any efiect for the time being.

Returning now to the finder selector link, Fig. 9, as a further result of sequence switch 600 moving into position 4, relay 616 energizes again over the following circuit: from ground by way of the upper right-hand contact of cam 226, Fig. 4, and said cam, lower 600 to battery. Sequence switch 600 now moves from position 4 to position 5.

\Vhen sequence switch 600 comes into position 5, a circuit is closed for sequence switch 200 of the incoming selector, Fig. 4, as follows: from ground by way ofarmature 572 of relay 567, Fig. 8, and its working contact, lower left-hand contact of sequence switch cam 580 and said cam, armature 575 and its resting contact, upper right-hand contact of cam 593 and said cam, lower lefthand contact of cam 593, conductor 857, cam 853 of the allotter sequence switch 850, Fig. 12, and its lower right-hand contact, conductor 865, lower left-hand contact of cam 642 of sequence switch 600, Fig. 9, and said cam, upper left-hand contact of cam 642, working contact of armature 619 and said armature, brush 669, conductor 251, lower right-hand contact of cam 229 and said cam, (Fig. 4) and the magnet of sequence switch 200 to battery.

Sequence switch 200 now advances from position 2 to position 3, whereupon cam 226 opens at its upper right-hand contact with circuit of relay 616, Fig. 9. Relay 616, upon deenergizing, closes a circuit for sequence switch 600 as followszfrom ground by way of armature 625 and its resting contact, upper. left-hand contact of cam 647 and said cam, and the magnet of sequence switch 600 I to battery.

tioned circuit for relays 655 and 570 in series is as follows: from ground by way of armature 629 of relay 614 and its working contact, upper left-hand contact of cam 649 and said cam, lower left-hand contact of cam 649, re-

. lay 655, conductor 466,1owerright-hand contact of cam 587 and said cam, upper righthand contact of cam 587, and the lower winding of relay 570 to battery.

Relay 655, Fig. 9, upon energizing over the above traced circuit,connects brushes 605 and 606 with conductors 468 and 467 at armatures 658 and-657, respectively. As a further result of the energization of relay 655, it closes a circuit for relay 616 as follows: from ground by way of the working contact of armature6 56 and said armature, lower righthand contact of cam 652 and said cam, upper left-hand contact of cam 652, and'the lower winding of relay 616 to battery. Relay 616, upon energizing, connects brush 608 with conductor 465 of the transfer control circuit at armature 624 by way of the upper righthand contact of cam 646 and said cam, upper left-hand contact of cam 646, armature 624 and its working contact, and cam 648 and its upper right-hand contact. This completes the connecting of the conductors .465, 467, and

. 468 of the common transfer control circuit to the corresponding conductors 753, 751, and 750, respectively, in preparation for the transferring of the stored number to the waiting sender. As a further result of the energization of relay 616, it closes a circuit for sequence switch 600 at armature 625 by way of the upper right-hand contact of cam 647 and said cam. When this occurs, se-

quence switch 600 moves from position 6 to position 7, whereupon the circuit of relays 570 and 655 is shifted so as to include the lower right-hand contact of cam 644 and said cam, armature 623 and its; working contact, upper right-hand contact of cam 649 and said cam instead of the lower left-hand contact of cam 649.

Asa further result of the sequence switch 600 moving into position 7, or to be more explicit, when the said sequence switch reaches position 6 a circuit is closed for sequence switch 850, Fig. 12, as follows: from ground by way of cam 640 and its lower left-hand contact, conductor 866, lower righthand contact of cam 855, Fig. 12, and said cam, and the magnet of sequence switch 850 to battery. Sequence switch 850' new advanccs from position 1 into position 2, thereby assigning finder selector No. 2 in case said finder selector is idle.

In the transfer control switch, Fig. 8, relay 570, upon energizing in series with relay 655, Fig. 9, as pointed out above, closes a locking circuit for its upper winding at armature 557 as follows: from ground by way of armature 572 and its working contact, lower left-hand contact'of cam 580 and said cam, lower righthand contact of cam 580, armature 557 and.

its working contact, and the upper winding of relay 57 O to battery. As a further result of the energization of relay 570, it places a shunt around cam 587 and its upper righthand contact at armature 576 so as to maintain the circuit of its own lower winding and of relay 655, Fig. 9, intact after the upper right-handcontact of sequence switch cam 587 has opened upon-sequence switch 550 moving out of position 1. As a still further result of the energization of relay 570, it closes a circuit for sequence switch 550 as follows: from ground by way of armature 572 and its working contact, lower left-hand contact of cam 580 and said cam, armature 575 and its working contact, lower left-hand contact of cam .57 9 and said cam, and the magnet of sequence switch 550 to battery. Sequence switch 550 new advances from position 1 to position 2, whereupon the thousands registration is transferredto the sender.

Before describing in detail how the registered number is transferred, the method used in transferring the number will be con-- sidered briefly. As explained hereinbefore, the three conductors 465, 467, and 468 of the transfer control circuit are connected through to the corresponding conductors 753, 751, and 750, respectively, of the sender, Fig. 10. In the sender, these conductors are at this time. connected to the thousands set of set-up relays comprising the four relays 811-814, inclusive. These four relays are pulled up orleft normal in any one of ten different combinations, depending upon the way in which the three control conductors are connected up in response to the thousands registration of the register B, Fig. 6. After the thousands registration is transferred, the hundreds registration is transferred to the set of hundreds relays comprising relays 821-824, inclusive. In the same manner, the tens and then the units registration is transferred.

The detailed description of the transferring of the number will now be given. When sequence switch 550 of the transfer control 

